1. Field of the Invention
The present invention relates to apparatus for cutting elongated filamentary material into shorter lengths and to method and apparatus for quickly and uniformly removing the cut material. More particularly, the invention relates to the regulation of air flow immediately beneath the doffing point of a staple cutter for nylon tow to achieve adequate yarn separation to permit the yarn to open properly in a subsequent carding process.
2. The Prior Art
Cutters as described by Keith in U.S. Pat. No. 3,485,120, hereby incorporated by reference, are broadly used for cutting tow into staple length fibers. These cutters include a rotatable reel having outwardly facing cutter blades against which the tow is wound and a fixed pressure roller pressing upon the tow wound around the reel resulting in cutting of the innermost layers of tow by the cutter blades. As cutting progresses a wad of cut staple fiber is forced inwardly between adjacent pairs of blades. Unfortunately, centrifugal forces and interfiber adhesion resist removal of wads of cut fibers by gravitational forces. Thus, the wads of cut fibers continue to rotate with the reel and continue to increase in size until either the cutter jams or until ropes or chips of cohered staple break off from the wads and fall into the collection hopper. These ropes or chips are heavily entangled, difficult to open, and cause subsequent difficulties in mill processing, such as carding.
Cook in U.S. Pat. No. 3 733 945, hereby incorporated by reference, recognizes the problem associated with the Keith cutter and resolves the problem by mounting at least one fixed jet so that it jets air downwardly upon the proximity of the doffing point of the cut fiber through aligned apertures in the cutting reel which rotate past the jet. This assists the gravitational forces in overcoming the effect of centrifugal and fiber-to-fiber forces allowing the cut fiber to fall freely downward. Cook also discloses several unsuccessful attempts to remove the cut staple, which include: inserting an air jet at the center point of the cutting reel directed outwardly so to impinge upon the pressure roll; placing a jet at the top of the chute directed inwardly at the vertical axis of the cutter; placing a plurality of jets around the circumference of the top of the chute, all directed inwardly of the vertical axis of the cutter; and inserting holes in the side of the chute and placing air jets therein directed to the vertical axis of the cutter and subsequently at a 45.degree. angle so as to be directed inwardly towards the interior of the cutting reel.
Potter in U.S. Pat. No. 4,120,222, hereby incorporated by reference, modifies the reel-type cutter of Cook so that the jet-producing orifices rotate with the reel and do not interrupt jet air flow as in Cook to reduce the noise level of the Cook arrangement.
Kayser et al. in U.S. Pat. No. 3,985,053, hereby incorporated by reference, utilizes a radial blower to avoid twist formation at the cutter. The radial blower is aligned with its suction opening as close as possible to the cutting point, care being taken that at least the major portion of the intake air flows from one or from combined cutting points. The blades of the blower rotor leave a space between fan blades and the inside wall of the housing corresponding to at least half of the effective knife lengths of the cutting point of the staple cutter preceding the radial blower.
Laird in U.S. Pat. Nos. 3,861,257 and 3,915,042, both of which are hereby incorporated by reference, discloses cutters the blades of which may face inwardly or outwardly. After the tow is cut it is forced radially outwardly into an annular chamber which surrounds the cutter reel and is connected to ductwork leading to the feed end of a blower. Openings are provided inwardly of the ring of cutter blades for admission of fluid such as air into the suction chamber. Thus, the blower draws air into the annular chamnber causing the air to flow radially outwardly through the spaces between the blades, entraining the cut fibers and carrying them through the ductwork and through the blower and outlet duct into a collection chamber.
Vehling et al. in U.S. Pat. No. 3,948,127, hereby incorporated by reference, provides apparatus for severing a continuous tow comprising a first cage around which the tow wraps and a second cage including a plurality of knives forming an annulus around the tow, the outermost convolutions of the tow being displaced radially outwardly to move into the range of and be severed by the cutting edges of the knives. The severed filaments are preferably withdrawn radially outwardly through the spaces between the knives by a suction chamber a portion of which surrounds the second cage.
Roncato in U.S. Pat. No. 3 945 280, hereby incorporated by reference, supplies compressed air to the spaces between cutting blades on a rotating drum to remove waste material resulting from the cutting of a tow carried by a rotating support drum operating in conjunction with the cutting blades.
Another cutter which utilizes air for staple removal is Hebeler in U.S. Pat. No. 2,607,418, hereby incorporated by reference. The present invention is an effective, alternate solution to the problem of cut staple removal.